Landing field localizer



lJuly' z, 1935.

' L. COHEN ET AL LANDING FIELD LOCALI ZER Filed June 3, 1929 2 Sheets-Sheetl l' July 2,'1935. col-IEN ETAL 4 LANDING FIELD LOALIZER Filed June s, 1929 2 sheets-sheet 2 if L IL" .M u MMM Loa W m a a. saw/ a/ M7 Mw/X. an. Jm W:

40 1 A derstanding that the several necessaryv elements Patented July 2, 1935 PATENT OFFICE LANDING FIELD LOCALIZER Louis Cohen, Joseph vvI. McMullen, and Joseph O.

, Mauborgne, Washington, D. C. l

Application .nine 3, i929, sei-iai No. 368,170 10 claims. '(cl. 177-352) This-invention relates in general to landing eld localizers employing signaling devices and more particularly has reference to a method and apparatusv for determining landing locations from aircraft.

Previous to this time, radio beacons have been provided for aiding a pilot in reaching an approximate destination. Under conditions of poor visibility, however, guidance of this character have not proved of any material advantage in aiding in the safe descent of a craft to the exact landing area.

'This invention consists in general of placing a plurality of separate conductors particularly spaced in parallel relation about the edges of a suitable landing area, transmitting separate currents of different characteristics through each individual conductor, and detecting, and distinguishing certain ofthe currentsset up either visually or audibly from an aircraft whereby the 'location of the field and the direction of flight maybe determined by the pilot in discriminating between the different signals.

An object of this invention is to provide a method and apparatus whereby aircraft approaching an air port may be guided directly to" the landing area.

Another object of ,thisinvention is to provide a method and apparatus whereby an aircraft over the landing area of an airport may be directed in-a proper course for landing.

A further object ofthis invention is to provide a method and apparatus which may be utilized in connection with high or low frequency alternating current or interrupted direct current systems. t With these and other objects in view which may be incident to our improvements, the invention consists in the parts and combinations to be hereinafter set forth and claimed, withgthe uncomprising our invention may be vvaried in construction, proportions and arrangement without departing from the spirit and scope of the appended claims.

In order to makeV our inventionA more clearly understood, we have shown in the accompany.- ing drawings means. for carrying the same into .practical eiect, without limiting the improvements in their useful applicationsy to the particullar constructions which, for the purpose ofexplanation, have been made the subject of illustration. Y

In the drawings forming a part of this specilicationz.

dotted lines a, a', b, b',

Figure 1 is a diagrammatic view of the landing n field of an airport showing the system of conductors forming the subject matter ofv this invention, in which direct currents are employed.

Figure 2 is a diagrammatic View of one form of a receiving system for installation on aircraft. l Figures 3 and 4 are diagrammatic views of circuits showing the arrangement for the use of high frequency'currents on the wires.'

Figure 5 is a perspective view showing a receiving arrangementsuitable for the reception of high frequency currents.

Figure 6 is-a front view showing one form of indicating instrument. l

Figure 7 is a perspective view showing a modication of the receiving arrangement in which a. resonance wave coil is used as a pick-up coil.

Referringv more particularly by numerals to the drawings and more especially to Figure 1, there is showna landing eld bounded by the The landingv areas proper are therectangles A, B, C, D or E, F, G,

Hyeither of which will be used depending upon T the direction of the wind near the surface of the earth. -.f A multiplicity of separate parallel wires suit- 1 ably spaced is placed outside of and parallel to each edge of the landing area. For the purpose of illustration, only three wires on each side of the landing area are shown. The wires on one side are indicated by I, 2 and 3; the wires on the second side of the eld by 4, 5 and 6; the wires on the third side of the eld by l, 8 and 9; and thoseon the fourth side of the field by I0, II and I2. l

Each individual wire is separately provided with a direct current source, an interrupter and a. signaling device. The description is confined to the arrangement of one wire only; the same by the device I4, which imparts a distinctive character to the current, determined by the frequency of the interruptions.

A separate direct current source is provided in each of the Wiresasat I3, I'I, I8, I9, 20, 2|, 22,

23, 24, 25, 26, 21, and likewise separate interrupters Il, 28, 29, 30, 3l, 32, 33, 34, 35, 36, 31, 38, which are adjusted differently so as to produce in each wire an intermittent current of a different character. The signaling device i5, in circuitA With the wire l may be in the form of an automatic telegraph key or other device, for continuously transmitting a characteristic signal, so that a signal of deiinite pitch and character is continuously emitted. The remaining signaling devices 39,60, di, d2, 13,` fill, llii, lit, di, d, Q9, are arranged each to produce signals of., different characters.

The current intensities in corresponding wires of the groups on the four sides of the landing eld are the same, as for example l, d, S and l2. The current intensities in thewires of any single group on any side, as i, 2, and 3 however, are different. The characteroi the currents which is determined by the frequency of interruption is also different for each of the twelve wires shown. Y

landing eld from any direction asthe same passes over the wires surrounding the eld emitting signals of diierent characteristics and thus the side of` the eld which the craft is ying 4over as well as the direction of flight ascertained, by

-manipulation of a directional coil to be later l described. A

The signaling devices, shown by boxes iii, 39, and im in the wires 8,-2 and 3, and corresponding signaling devices in the wires on the other three sides of the eld, may be of any suitable type. For auditory signals each may be designed to emit a combination of dots and dashes or other characteristic auditorysignals which willlbe recognized by the-aviator as the signal characteristic of the particular wire. If a visual indication is desiredany suitable equipment, such for 'example, as a vibrating reedA instrument'may be employed, in which instance the signaling devices could be eliminated from all the wires.

It is suicient in such installations to provide an instrument on the aircraft having a number of indicating elements, such as vibrating reeds, each one of which responds only to one of the frequencies of the intermittent or low frequency currents in the wires, thus discriminating between the signals in the. various wires.

It is also to be noted` in this'connection that low frequency current may be introduced inthe several individual wires and the direct current sources and interrupters also dispensed with. In installations of this character the signal characteristlcs of each wire will also be different, likewise using signaling devices already described with reference to interrupted direct current system.

For illustration there are depicted two airplanes 5B and 5l shown approaching the landing field, having an interrupted direct current or low frequency installation. These airplanes are provided With direction finding coils 52 and 53 for' picking up the signal emanating from the several sets of separate wires surrounding the eld.-

A fiat spiral coil 54 corresponding to the coils A 52 and 53 is shown in Figure 2in greater detail.,

The coil is adapted to be mounted either within the aircraft or suspended from it and by induction is adapted to pick up energy from the successive wires on the landing ileld as the aircraft passes over the same. A

The terminal wires 55 and 55 of the coil are connected to a suitable indicating instrument 51 which responds differently to the currents induced in coil 54, by the magnetic'iield of the currents in the field wires which are characterized by -suitable means.

rents in the successive' wires.

vacuum tubeamplier 58', `or other ty-pe of amplier may be interposed so that the: signal intensities may be' increased so that a more dis. tinct reception of the signal may be secured.

The c'oil 5ft is adapted to be oriented with ,respect to the direction of the field wires. angularI position of the coil 54 is observed on a scale 59 with reference to a pointer 60. Turning of the coil is eiectedby .a kob 6l controlled Within the aircraft or remotely operated-by any In rotating the coil the same may be positioned 'parallel to the field wires to aiord the maximum intensity of reception and the relative course of the aircraft withprespect to the particular field wire ascertained by inspection'of the position'of 20 the pointer on the scale. lt' will be appreciated that in .leveling oi for landing Ithe longitudinal axis of aplane should be in line with the direction of flight. It will be readily'apparent that if the longitudinal axis of a plane is angularly dis- '25 posed in relationv to the'direction of iiight the vlanding gear will be similarly out' of line and that on contact with the ground disastrous results such as taking off the landinggear or ground looping are apt to occur. ,Y

In accordance with this'invention the direc- .tional relation of the longitudinal axis of a plane to the source of thesignal is determined by rotat- `ing the coil and correcting for any angular devia'- tion from if such exists. lhe utility of the '35 the aircraft either one or moreof these vibrating 45 reeds will respond depending upon the height of the aircraft, spacing of the wires and the relative Y intensities'of the current in the wires.

.A telephone receiver, in which the signals emitted by the eld wires are made audible, and are 50 differentiated either by the difference in pitch or the combination of dots and dashes or other characteristic signals transmitted from each individual wire,.may be substitutedjor the reed instrument.

In using a vibrating reed indicator, the reed which is adjusted for resonance with the frequency of the current in the extreme outer Wire will be the first to respond, and as an aircraft approaches in descent to `the landing field, other 60.

vibrating reeds will-be brought into action'which are in resonance with the frequencies of the curv It the eld is. appreached on a line coincident with the diagonal,

the corresponding reeds -in each series will, of 65 course, vibrate to inform a. pilot with respect to his location and the relation of his direction of flight to a particular boundary of a landing fleld. The advantage tb be obtained in using an indicator ofthis character is that the reeds'do not 70 I brought down to pick up suicient current inten-A 75\ The l() in the form 40 A suitable vibrating reed` instrument 80 is shown in Figure 6. Twelve separate reeds, each one of which is adjusted to respond to a different signal frequency emitted by one of the wires, are

employed. The reeds are vso arranged that the rst three marked N respond respectively and' successively to the signals of the three wires 1ocated on the north `side of the eld, the second three reeds lettered E, responsive respectively and successively to the signals of the three wires onl the east side ofthe field, the third three reeds designated S, responsive respectively and successively to the signals of the three wires'on the south' side of the field, and the last three reeds grouped under W, responsive respectively and successively to the signals of the three Wires onthe west side of the Afield. Y

In this manner a visual indication may be had from within an aircraft of the relation of the same with respect to the landingeld as the wires are passed over in succession. Also, the direction of the craft with respect to the boundaries of the landing area may be observed by reference to position of the pointer 60 carried by the coil 54 on the scale 59. The additional information concerning the direction of the wind on the ground may be given tothe pilot by radio, so that'he is advised by the signals emitted from wires how to orient the plane in order to land in the proper direction.

The operation of this device will` be readily understood with reference to Figure 1. In providing different current intensities in `the field wires in the manner described, an airplane, as 50 or 5I, or other aircraft, nearing a landing field will iirst receive an indication from the extreme outer wire,'-.

' field, in order to check his observation as to his angle of approach, after which he would orient himself to place his craft on a proper course for landingpwith respect to direction of the wind which had been signaled to him from the ground.

After" the pilot has oriented himself andas' the aircraft approaches more closely toward the landing field, the pilot is guided Yin hisv descent by the signals-A from the succeeding wires in which the signals are'of successively lower intensity.

By 'this arrangement, a funnel location method isprovided, that is, signals of different character are made` evident to a pilot' in approaching in descent toalanding field. `In nearing the extreme outer wire, a pilot is also able to orient` the position of the aircraft by. the adjustment of ,the pick-up coil 52 or 53 in Figure 1,.or' 544 in Figure 2, until the aircraft is brought in proper relation tothe course that desired Ato pursue in approaching the landing field so as to land into the wind. The signals in the dierent wires thus afford a means to the aviator for guiding him 'in his approach and descent to the landing eld. It will also be manifest from the above ,that an approximate estimate ofthe altitude may be had by correlating the decreasing intensities of the signals emitted by the successive wires on a suitable indicating instrument.

Radio aswell as audio frequency currents may beemployed as will be noted with reference toI the arrangement shown in Figure 3, in which a system f Wires for only one side' of the eld is shown. AIt is to be understood that it is intended to install similar systems of wires with properly associated circuits which are similarly arranged for each of the other three sides of the landingV field, in the manner' as shownu in Figure 1.

In Figure 3, threewires I, 2 and 3 are shown on one side of the eld, a a' and b b', each of which wires is connected in series with a variable condenser 62, 63 and B4, respectively, variable inductances 65,- B6 and -II, respectively, and ground terminals I6, the other end of the wires being open. High' frequency transmitters 68, 69 and 10, associatedY with suitable modulating means, are coupled to the three wire circuits I, 2 and 3, respectively. v Any of the conventional modes of generating the high frequency oscillations, and any of the usual methods for modulatingthese high frequency oscillations eithertelephonically, telegraphically, or otherwise, may be utilized.

It is intended that all the transmitters which act on the various wires on all sides ofthe landingl eld, operate on the same frequency, but that each of the transmitters be modulated to impart a dierent character to the signals. If telephonie modulation isemployed, different telephonie sig'- nals may be employed to distinguisheach of the Wires. If the same radio frequency is used for all the transmitters, only a single receiver on the aircraft is required to receive the signals from all of these ywires without any variation in adjustment Also, as signals of a different character are emitted from each of the wires, the signals emitted from the different wires are differentiated between. l

vThe intensities of theoscillatory currents in the Vwires may be either the saine or different.

This may be accomplished by varying the cou'- plings between theA transmitters and the respective wires with which they are associated, orvby the adjustment of the power output of each' of 'these transmitters, or by a combination of the two, lor in. any other suitable manner. VIt is preferable, however, that the intensity of the oscillatory currents in the outer wires should be of the vhighest value, and that the current intensities should decrease successively in the different wires as the actual landing field proper is ap- .proached The corresponding wires on the oppo-, -site'sides of the field, however, should have thev coils 1l and 12. 'I'he tw ends of each wire may suitable means.

be either left open or -grounded through two separate condensers 15 and 15, or under suitable conditions, grounded directly. f

It ls'to be understood that each transmitter is associated with a suitable modulator in accordance with the description in connection with Figure 3. I'he difference between the arrangements shown in Figures 4 and 3 consists only in applying in Figure 4 the high frequency oscillatory energyto the center of each of the Wires, rather than to one terminal of the wire as shown in Figure .3.

The arrangement used for receiving the high frequency signals emitted from the wires on the landing field on an airplane 50, for example, is shown in Figure 5. A loop antenna 16 is suspended from the airplane or may be placed within therfuselage or at any other suitable location, and the same connected to a suitable receiver 11, which is provided with a suitable amplifier and suitable indicating means. The indicating device 18 may be a vibrating reed instrument as heretofore described, or a radio telephone receiver, in which the signals emitted from the different wires are made audible and distinguishable, or 'any other vsuitable form of indicator. The loop antenna 16 is mounted in a matter to be rotatable about its vertical; axis, the rotation of which is accomplished by a handle 19, or other number of turns wound in the form of a long coil and'properly adjusted for response to the particular signal frequency which is to be received, may be employed in place of the loop. A coil 8l of this type is shown in Figure?` connected at one point to the receiver 11 which is' associated with a suitable indicating instrument 18. The resonance wave coil 8l is mounted so that its axis is parallel to and so that it can be rotated in a plane substantially parallel'to the plane of the wings. This form of antenna is well adapted for the purpose in that a highlyefiicient energy collector is not required, and this wave coil antenna because of its high selectivity and because ofits directional properties is very suitable for use in connection with landing field localization. This instrument is operated in the same manner asv has already been described with reference to the loop 1S.

In the several figures only three wiresv on each side of the field have been illustrated, and vibrating reed instrument comprising only twelve reeds corresponding to the signals emitted from the twelve wires placed around the field described as a suitable receiving device, but it is to be understood that no fixed limitation is placed on the number of wires that may be employed and the corresponding number'of reeds that may be required. These would depend upon the matter of field space available, and also upon other practical considerations that would have to bemet in an installation of this character.` 1

-The wires may be located either under or on i the surface of the ground, or even at Asome height The adjustment of theposition acoaore cated outside the landing courses proper, and

since it is generally required in every good landing-field that there should be considerable vacant and clear space surrounding the landing field, the placing of these wires around the eld will not produce any considerable hazard or obstacle to landing in the eld proper.

There is accomplished by this invention a method and apparatus whereby aircraft appreaching an air port under conditions of poor visibility may be guided 'directly to a landing area and directed in a proper course for landing, utilized in connection with high or low frequency or interrupted direct current systems.

. Whilewe have shown and described the preferredembodiment of our invention, We wish it to be understood that we do not confine ourselves to the precise details of construction herein set forth, by way of illustration, as it is apparent that many changes and variations may be made therein, by those skilled'in the art,without departing from the spirit of the invention, or exceeding the scope ofthe appended claims.

We claim:

l. A method of directing the landing of air-V craft in fog, comprising transmitting separate signalsV of different characteristics along each side of a landing 4area to identify the directional boundaries thereof, and detecting and distinguishing the character and direction of the signal over which the aircraft is fiyingto indicate to a pilot the location and direction of ight of the aircraft with respect to the source of the signal, thereby to orient the pilot 'with respect to the locationand direction of ight of the aircraft in relation t'o the landing area.

2. A method of directing the landing of 'aircraft in fog, comprising transmitting a plurality of parallel groups of.v spaced signals of di'erent characteristics along each side of a landing area,

the signals in each group being of successively lower intensity toward the landing area to identify the directional boundaries thereof, detecting and distinguishing the character, direction and intensity of the signals over which the aircraft is flying'to indicate to a pilot*l the location and direction o f the flight and'altitude of the aircraft with respect to the source' of the i, signal thereby to orient'the pilot with respect to the location anddirection of flight of the aircraft in relation to the landing area, and checking the finding on the reception of successive signals toward a landing with respect tothe 'character and direction of the signals to check on the location and direction of flight, and the diminishing intensity ofthe successive signals for losing altil indicate to a pilot the location and direction of v of a. landing area to identify the vdirectional boundaries thereof, the signals in each group being of successively lower intensity toward the landing area, and means to detect and distinguish the character, direction and intensity of the signal over which the aircraft is ying toindicate Atoa pilot the location, direction of flight, and' altitude of the aircraft with respect to the signal thereby to orient the pilot with respect to the location 'and direction of fiight of the aircraft in relation to the landing area, the subsequent reception of' successive signals being adapted to afford a check of the nding on the first signal with respect to the character and .direction of the signal, the reception of signals of successively lower intensity affording a guide f or the pilot to lose altitude for landing on the area.

5. An apparatus for directing the landing of aircraft in fog, comprising separate radioantenna along each side of a landing area for transmitting signals of different characteristics to Aidentify the directional boundaries of the area,

and means to detect the signal, over which the aircraft is iying to indicate to a pilot the location of the aircraft vwith respect` to the antenna thereby to orient the pilot with respect vto the location and direction of flight of the aircraft in relation to the landing area.

6. An apparatus for directing the landing of aircraft in fog, comprising separateradio antenna along each side ofa landing area for transmitting signals of different characteristics to identify the directional boundaries of the area and means to detect and distinguishthe character anddirection of the signal over which the aircraft is flying to indicate to the pilot the location and direction of the flight of the aircraft with respect to the location Vand direction of the antenna thereby to orient the pilot with respect `to the location and direction of ight of the aircraft in relation to the landing area.

'1. An apparaus for directing theA landing o f aircraft in fog, comprising means to transmit separate radio signals of different characteristics along each side of a landing area to identify the directional boundaries thereof, a radio detector tinguish the signal over which the same is flying to indicate to a pilot the location and the direction of flight of the aircraft with respect to the landing area, and a radioreceiver to detect and distinguish the character and direction and intensity of the signal over which the aircraft is ying to indicate to a pilot the location, direc-` tionof flight and altitude of the aircraft with respect to the source of the signal thereby to orient' the pilot with respect to thelocation and direction of .flight of the aircraft in relation to the landing area, the subsequent reception of successive signals being adapted to afford a check on the finding of the rst signal with respect to the character of the signal and the direction of ight of the aircraft in relation thereto, Vthe reception of'signals of successively lower intensity being adapted to afford a guide for the pilot to lose altitude for bringing the aircraft to a landing on the area.

9. A landing area having apparatus installed along eachside thereof for transmitting signals of different -characteristics to identify the directional boundaries thereof, for detection .on aircraft iiying in fog.

10. A landing area having separate groups of parallelly arranged apparatus installed along each different characteristics to identify the directional boundaries thereof and different 'intensity for reception on aircraft so that the aircraft may lose altitude in accordance therewith for landing.

LOUIS COHEN. JOSEPH I. MCMULLEN. JOSEPH O. MAUBORGNE. 

